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Pulmonary arteriovenous malformations (PAVMs) are abnormal communications between the pulmonary arteries and veins, which result in a right-to-left (R-L) shunt with resultant hypoxemia, the severity of which will depend upon the size and number of lesions. Most PAVMs occur in individuals with hereditary haemorrhagic telangiectasia (HHT) and are a cause of serious morbidity and mortality largely related to cerebrovascular complications secondary to paradoxical embolization. The importance of their recognition and treatment by embolization, even in the absence of symptoms, is well known. Their appearances on chest radiographs are often, but not always, characteristic and the CT appearances are diagnostic; however, there are a number of both vascular and non-vascular diseases that can cause confusion. This review serves to highlight these PAVM "mimics". [ABSTRACT FROM AUTHOR]

Sarcoidosis has a wide spectrum of appearances within the thorax. This review will discuss and illustrate the range of pulmonary manifestations on high-resolution computed tomography and chest radiography, concentrating on atypical features and examples of sarcoidosis mimicking other lung diseases. All included cases have been histologically confirmed. Such variable imaging appearances should alert the radiologist to consider sarcoidosis as a differential diagnosis in the context of interstitial lung disease. [ABSTRACT FROM AUTHOR]

Aim: To investigate whether automated diameter assessment was feasible for CT colonography. Materials and Methods: Two experienced observers independently measured the maximum diameter of 50 polyps (colonoscopic reference size range 5-12 mm) from colonography datasets using conventionally placed software callipers and a variety of two-dimensional (2D) computed tomography (CT) window settings (colon, abdominal, bone, lung), and also three-dimensional (3D) perspective rendering. Polyps were also measured using automated polyp-segmentation software. Agreement between observers and with the colonoscopic reference measurement was determined using Bland-Altman, Wilcoxon, and Mann-Whitney U analyses. Results: Inter-observer agreement was similar for all window displays: mean difference in millimetres (SD difference; 95% limits of agreement) ranged from 0 (1.7, -3.3, 3.3) for 2D colon to -1.1mm (1.6, -4.3, 2.0) for 3D, compared with -0.5 (2.09, -4.6, 3.6) for automated measurement. When compared to colonoscopy, the largest discrepancy occurred using the 3D display (mean difference 1.3mm, 2.5mm for each observer). There was also a significant difference between estimates and reference size when using the 2D abdominal and 3D displays (p=0.03, <0.001). Conclusion: Automated polyp measurement is possible in vivo. Automated and conventional methods have comparable inter-observer agreement. The greatest measurement error is encountered when using a 3D display for estimates of diameter. [ABSTRACT FROM AUTHOR]

Aim: To assess the effect on radiologist participation in learning from discrepancy meetings (LDMs) in a multisite radiology department by establishing virtual LDMs using OsiriX (Pixmeo)., Materials and Methods: Sets of anonymised discrepancy cases were added to an OsiriX database available for viewing on iMacs in all radiology reporting rooms. Radiologists were given a 3-week period to review the cases and send their feedback to the LDM convenor. Group learning points and consensus feedback were added to each case before it was moved to a permanent digital LDM library. Participation was recorded and compared with that from the previous 4 years of conventional LDMs. Radiologist feedback comparing the two types of LDM was collected using an anonymous online questionnaire., Results: Numbers of radiologists attending increased significantly from a mean of 12±2.9 for the conventional LDM to 32.7±7 for the virtual LDM (p<0.0001) and the percentage of radiologists achieving the UK standard of participation in at least 50% of LDMs annually rose from an average of 18% to 68%. The number of cases submitted per meeting rose significantly from an average of 11.1±3 for conventional LDMs to 15.9±5.9 for virtual LDMs (p<0.0097). Analysis of 35 returned questionnaires showed that radiologists welcomed being able to review cases at a time and place of their choosing and at their own pace., Conclusion: Introduction of virtual LDMs in a multisite radiology department improved radiologist participation in shared learning from radiological discrepancy and increased the number of submitted cases., (Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Aim: To assess the effect of changing from an "appointment" to a "same-day" ultrasound (US) service on referral pattern, departmental workload, and patient satisfaction., Materials and Methods: To reduce US waiting time of 3 weeks for routine examinations, a "same-day" service was started for outpatients and general practitioner (GP) patients in September 2006. To examine the effect of this change a retrospective assessment was performed of workload during 1 week in June 2006 (appointments only) and the same week in 2008, 22 months after the implementation of the new service. Distance travelled by patients and waiting time was recorded. Patient satisfaction with the service was assessed by questionnaire in September 2008., Results: Hospital referrals remained stable, but GP referrals increased from 99 to 367 (270%) and distance travelled by patients increased from a median of 3.1 km (range 0.1-12.1 km) in 2006 to 4.8 km (range 0.2-19.8 km) in 2008 (p<0.001). Non-local GP referrals increased from 20/99 in 2006 (20%) to 198/367 in 2008 (54%). The increased workload was managed by flexible working by radiologists and two additional sonographers. Departmental waiting time increased for all patients with same-day patients waiting a median of 35 min (interquartile range 19-60 min). Ninety-one percent (79/87) of same-day patients rated the service excellent or good, but many requested better information on the waiting time., Conclusion: There is a demand from GPs for same-day US, and it is feasible in a large hospital with flexible radiology working and increased sonographic staffing. Unless adjacent hospitals offer a similar service, continuing rise in demand could overwhelm the service., (Copyright 2009 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Aim: To externally validate a computer-assisted detection (CAD) system for computed tomography (CT) colonography, using data from a single centre uninvolved with the software development., Materials and Methods: Twenty-five multi-detector CT colonography examinations of patients with validated polyps accumulated at a single centre were examined by two readers who used endoscopic and histopathological data to identify polyp coordinates. A CAD system that had been developed using data from elsewhere, and had not previously encountered the present data, was then applied to the data at sphericity filter settings of 0.75 and 0.50 and identified potential polyps. True-positive, false-negative, and false-positive counts were determined by comparison with the known polyp coordinates., Results: Twenty-five patients had 57 polyps, median size 6mm (range 1-15mm). Per-patient sensitivity for the CAD system was 96% (24 of 25). The CAD system detected 44 (77%) polyps at sphericity setting 0.75 and 49 (86%) polyps at sphericity 0.50: the additional five polyps detected all measured 5mm or less. Sphericity of 0.75 resulted in a median of 10 (one to 34) easily dismissed false-positive prompts per patient and a median of 4 (zero to 15) that needed three-dimensional rendering before dismissal. This rose to 32 (16 to 99) and 11 (three to 35), respectively, at sphericity 0.5., Conclusions: A per-patient sensitivity of 96% was found for the CAD system (in patients with a median polyp diameter of 6mm) using external validation, a more stringent test than either internal cross-validation or temporal validation. Decreasing sphericity increases sensitivity for small polyps at the expense of decreased specificity.

Objective: The aim of this study was to define the relationship between interpleural distance measurements on an erect posteroanterior chest radiograph and pneumothorax size as measured by helical CT in a series of patients., Subjects and Methods: Twenty pneumothoraces from 19 patients (10 males, nine females) were analyzed. Most pneumothoraces were on the right side (n = 16). The etiology was spontaneous in seven patients and iatrogenic in thirteen. All patients underwent an erect inspiratory posteroanterior radiograph and a helical CT scan of the thorax on the same visit to the radiology department. The interpleural distance was measured at three locations and the figures added together. Following helical CT of the thorax, the percentage pneumothorax size was calculated by drawing regions of interest around the relevant hemithorax and lung on 10-mm reconstructed slices. A scattergram of the sum of interpleural distances in centimeters versus percentage pneumothorax size was plotted., Results: Analysis of results showed that percentage pneumothorax size could be calculated by the formula Y = 4.2 + [4.7 x (A + B + C)], r = .98, p < .0001., Conclusion: This study identified a formula for accurately calculating percentage pneumothorax size as determined by helical CT from an erect posteroanterior radiograph. Using this formula with the clinical status of the patient should more easily identify patients requiring active intervention.

Purpose: In this retrospective multicenter study, the authors analyzed the clinical efficacy of different metallic stents in the palliative treatment of patients with neoplastic obstructive jaundice., Patients and Methods: Two hundred forty patients were treated in four European centers. Causes of obstruction were pancreatic carcinoma (n = 84), biliary neoplasm (n = 99), metastases in hilar nodes (n = 34), primary or secondary liver tumors (n = 4), and other tumors (n = 19). A total of 388 metallic stents were used: 300 Wallstents, 35 nitinol Strecker stents, 40 Gianturco-Rosch Z stents, and 13 tantalum Strecker stents., Results: Overall 25- and 50-week survival rates were 42% and 16%, respectively; the 30-day mortality rate was 14.6%. Two deaths were related to the procedure (0.8%); 19 patients (8%) had major complications. The 25-week patency rate was significantly higher for the nitinol Strecker stents and the Wallstents (78% and 67%, respectively) than for the Z stents and the tantalum Strecker stents (30% and 20%, respectively) (P < .01 and P < .001, respectively). Average patency was 8.3, 5.9, 2.3, and 4.0 months, respectively. Reintervention due to stent obstruction was necessary in 53 patients., Conclusion: The Wallstent and the nitinol Strecker stents were the most effective in achieving long-term palliation. Patency was significantly affected by the level of obstruction but not by the type of obstructing tumor.

The development of self-expanding metallic endoprostheses which can be implanted easily, with minimal trauma, has revolutionized the non-surgical treatment of both benign and malignant biliary strictures. The Wallstent (Medinvent SA, Lausanne, Switzerland), a pliable, tubular stainless steel mesh, is the metallic stent of choice for treatment of malignant strictures and can be implanted in a single session resulting in a shortened hospital stay for patients undergoing palliation of irresectable biliary tumours. Although follow-up is currently rather limited, it appears that the occlusion rate of Wallstents will be lower than that of plastic endoprostheses and no cases of stent migration have been reported. The Gianturco zigzag stent (Cook Inc., Bloomington, Ind, USA) should not be used in malignant strictures because of rapid occlusion due to tumour ingrowth through the struts. However, it exerts a strong, continuous, outward radial force and is ideally suited for use in the small, but difficult to manage, group of patients with benign biliary strictures which recur despite surgery and repeated balloon dilations.

During a 28-month period, the authors placed 91 Wallstent endoprostheses in 55 patients with malignant obstructive jaundice. Five patients developed recurrent jaundice between 2 and 60 weeks after stent insertion due to stent occlusion by tumor overgrowth on seven occasions. To assess long-term segmental side-branch drainage through the walls of such endoprostheses, the cholangiograms obtained following stent occlusion were reviewed. In all five patients, evidence of drainage of intrahepatic ducts through the side of the mesh was observed. Although the number of patients in the series is small, this initial experience suggests that long metallic endoprostheses can be placed peripherally in the intrahepatic bile ducts without the potential risk of infection or occlusion of undrained, noninvolved segments. This policy may delay or prevent endoprosthesis occlusion in many patients.

Acute cholecystitis is a common condition which may be difficult to diagnose with confidence on clinical grounds alone. A large number of techniques are now available for imaging the gall bladder but, in practice, ultrasonography and cholescintigraphy are of greatest value. The former is cheap, readily available and features such as the presence of gall stones, gall bladder wall inflammation and a positive sonographic Murphy sign strongly suggest the diagnosis of acute cholecystitis. In addition to its diagnostic uses, ultrasonographically guided percutaneous cholecystostomy provides an alternative and sometimes life-saving form of treatment in those patients who are unfit for surgery. Cholescintigraphy is a highly accurate, non-invasive method for assessing patency of the cystic duct but is not always available in the emergency situation and takes longer to perform than an ultrasound examination. Acute cholecystitis, however, has many manifestations and may be calculous or acalculous, be associated with a patent or obstructed cystic duct, and may be complicated or uncomplicated. Imagining modalities other than those mentioned above may be useful in certain circumstances and this chapter aims to present the advantages and disadvantages of each technique in order to provide guidance for the clinician caring for a patient with suspected acute cholecystitis.

Duodenocaval fistula is exceedingly rare. Penetrating trauma, gunshot wounds and toothpick perforation of the duodenum are known aetiological factors. Two recent case reports have implicated radiation-induced ulceration of the duodenum. We describe the first case of duodenocaval fistula resulting from a giant peptic ulcer of the descending duodenum.

Symptoms caused by malignant hilar bile duct tumors are often palliated by the insertion of a percutaneous biliary endoprosthesis. However, these often occlude early and may be difficult to replace. We have reviewed our experience with percutaneous replacement of endoprostheses in 17 patients with 31 episodes of stent dysfunction. The stent was changed successfully in 30 of the 31 attempts. The average durations of initial and subsequent stent patencies were 28 and 20 weeks, respectively. Significant acute complications occurred in three patients, one of whom had a perihepatic abscess and two of whom had septicemia. Two patients died within 30 days of their last stent change. The one patient in whom attempted insertion of a new stent was unsuccessful had to remain on continuous external catheter drainage. The occluded or migrated endoprosthesis was successfully removed either percutaneously (55%) or endoscopically (26%) in 25 of the 31 cases. Successful removal of the stent and reinsertion after blockage or migration is possible in most patients. Our experience suggests that patients with malignant obstruction of the bile duct should not be refused an indwelling endoprosthesis just because of the frequent occurrence of early occlusion of the stent.